An apparatus for generating fumes of ammonium chloride has long been in use for the relief of affections of the upper nasal passages. I am indebted to my friend Dr. W. M. Mew, of the Army Medical Museum, for the following suggestions as to the mode of preparing the vapor for inhalation in suitable cases:

"Of course, putting two open vessels, containing respectively HC1 and NH3, would result in giving off fumes, but the supply of almost imponderable smoke would be so small as to be wholly inadequate for therapeutical purposes. My plan is therefore to set free a large amount of HC1 by decomposing NaCl with strong H2S04, yielding gaseous HC1 and leaving a residue of Na2SO4 in the containing vessel, usually a soup-plate. A saucer (used to distinguish it from the acid container to avoid mistakes) containing stronger ammonia is placed by the side of the soup-plate, and at once the room is filled with the smoke. . . . Generally I direct that three or four ounces of the acid are to be poured into the soup-plate, and about the same quantity of the ammonia into the saucer, and without loss of time about a tablespoonful of table-salt is sprinkled on the acid. Decomposition takes place at once. Some precautions are necessary here; should there be an excess of HC1 liberated (which would irritate the nasal passages), more NH3should be used. An excess of NH3 would be in evidence by its odor, requiring more salt or more acid. The neutral or properly balanced salt does not irritate the most delicate membrane. . . . By the occasional addition of a little salt, or acid, or ammonia, this can be kept up for hours—from four to six hours."

The air of the apartment charged with the fumes, the inhalation can go on from four to six hours or longer.